The present invention relates generally to signal acquisition and, more particularly, to correction of a non-linear signal.
Various electronic sensors, data acquisition systems and other electronic systems using a bandgap reference for data processing are used in a variety of applications, such as for acquiring information in manufacturing, testing, analysis and other experimental and industrial applications. In these and other applications, obtaining accurate data is important.
Particular applications for which data collection is important include sensing various characteristics, such as temperature, pressure and others. In many applications, a bandgap voltage reference forms an essential part of a sensor system. The voltage reference provides the reference signal that is used to convert the sensor""s characteristic dependent voltage into the digital domain. Given the availability of an accurate signal in the form of a voltage, the overall accuracy of a sensor is determined by the accuracy of the bandgap reference.
For example, many conventional bandgap references show a non-linear dependence, or curvature. This curvature causes a non-linear temperature dependent error in the output of a sensor based on such a bandgap reference. Many methods have been used to correct the curvature of a bandgap reference circuit, though not necessarily in the context of a sensor. Example categories of such methods include methods that change the bias current of the bipolar transistors in the reference and methods that generate a non-linear correction signal that is added to the output of the original reference; e.g. a piece-wise linear correction, an exponential correction, or a quadratic correction.
In these and other methods, many cancellation methods are limited in use to specific applications. These challenges inhibit the ability to obtain an accurate signal in a variety of applications.
The present invention is directed to the correction of a non-linear signal in various applications. The present invention is exemplified in a number of implementations and applications, some of which are summarized below.
According to an example embodiment of the present invention, a non-linear output signal from a data acquisition circuit is corrected using a bipolar transistor circuit having a base-emitter voltage. A corrected output corresponding to a detectable characteristic is determined as a function of the base-emitter voltage, an input corresponding to the detectable characteristic and the divisions of a plurality of division circuits. The corrected output exhibits a cancelled non-linearity of at least second order.
According to another example embodiment of the present invention, a system is adapted to provide a corrected output signal from a data acquisition circuit using bipolar transistor circuit having a base-emitter voltage, wherein the output signal corresponds to a detectable characteristic, such as temperature, pressure or other characteristic and exhibits a cancelled non-linearity of at least second order. The system includes a signal generation arrangement adapted to generate a non-linear signal. The generated non-linear signal is adapted to cancel a non-linearity of the output signal. A correction circuit is adapted to provide a corrected output corresponding to the detectable characteristic and to determine a corrected output as a function of the base-emitter voltage, the non-linear output signal and the generated non-linear signal.
In another example embodiment of the present invention, two or more division circuits are used in a data acquisition system to improve the output of the system. The division circuits are used in conjunction with a plurality of input signals to produce an output signal that exhibits corrected non-linear signal that represents a parameter upon which at least one of the input signals depends.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and detailed description that follow more particularly exemplify these embodiments.